The present invention relates to a suspension controller for a vehicle, and more particularly relates to a suspension controller which is effective for absorbing a particular kind of vibration of unsprung mass including resonant vibration of the unsprung mass. Here, the unsprung mass means the mass of a wheel and the vibration of unsprung mass means the vibration of the wheel when the vehicle is lifted so that the wheel is not on the ground.
Characteristics of a suspension member installed between a wheel and a body, e.g., spring constant, damping force of a shock absorber, stiffness of a bush, etc., have been determined under various conditions examined in consideration of both improvement in riding comfort, and improvement in drivability and stability.
According to the experiment in the recent year, however, an invention has been proposed whose object is to provide a suspension controller which attains both good riding comfort and improvement in drivability and stability of the vehicle that are abmivalent to each other, by altering the suspension characteristic in response to the road conditions, and the running condition of the vehicle so as to evaluate good riding comfort under some conditions while evaluating improvement in drivability and stability of the vehicle under other conditions. Examples of such inventions are disclosed in "Variable Damping Force Shock Absorber" (Japanese Published Unexamined Patent Application No. Sho 58-30542) for realizing good running condition by increasing the damping force when the vehicle is heavily loaded or running on a rough road, and "Vehicle Height Adjusting Apparatus" (Japanese Published Unexamined Patent Application No. Sho 57-138406) for automatically adjusting vehicle height by raising the vehicle height against a rough road while lowering it for a flat road.